Black & Decker Powerfile Rubber Narrow Pad Arm KA900E XTA900EK KA902E

Black & Decker Powerfile Rubber Narrow Pad Arm KA900E XTA900EK KA902E 

This pad sits on the bottom of the arm and is there to protct the arm from being damaged when the belt is used and acts as a buffer, you would need to replace this when the pad wears down.

Please see below applicable models